A stent graft can be deployed into the vasculature of a patient to repair a defect in the vasculature such as an aortic dissection or an abdominal or thoracic aortic aneurism.
Some stent grafts for the treatment of aortic dissections or an abdominal or thoracic aortic aneurysms include an exposed stent extending distally or proximally from the stent graft. Such a stent graft can include one of more barbs to assist with retention of the exposed stent into the vasculature of a patient and hence to prevent inadvertent or early engagement of the barbs with the vasculature when deploying the stent graft and introduction device for the stent graft may include a capsule which encompasses the exposed stent and the barbs. To release the exposed stent the capsule is moved relative to the stent graft and exposed stent.
It is desirable, however, that premature release does not occur and hence it has been proposed to use a release wire which passes through an aperture in the capsule and engages part of the exposed stent within the capsule.
This arrangement does not prevent relative rotation of the stent graft with respect to the introduction device and capsule nor can it entirely prevent premature release. Rotation of the exposed stent within the capsule can also cause entanglement of the struts of the exposed stent which can cause problems on deployment.
The object of this invention is to provide a safety release mechanism such as a stent graft retention system to at least prevent premature release of the stent graft and particularly the exposed stent from the capsule. It is a further object to prevent undesirable rotation of the stent graft with respect to its retention mechanism.
Throughout this specification the term distal with respect to a portion of the aorta, a deployment device or a stent graft or prosthesis is the end of the aorta, deployment device or stent graft further away in the direction of blood flow away from the heart and the term proximal means the portion of the aorta, deployment device or end of the stent graft nearer to the heart. When applied to other vessels similar terms such as caudal and cranial should be understood.